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Immutable types

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Nikhil Purushe edited this page May 24, 2016 · 17 revisions

You can combine requery annotations (and even JPA annotations) for use with immutable types. However there are some limitations to consider when using immutable types:

  • Immutable types cannot contain relational links (however you can have foreign keys)
  • Immutable types cannot have lazy loading or change tracking
  • Immutable types must have a static create method or be buildable via a builder class

Example using Google AutoValue defining a mapping:

@Entity
@AutoValue
public abstract class Person {

    @AutoValue.Builder
    static abstract class Builder {
        abstract Builder setId(int id);
        abstract Builder setName(String name);
        abstract Builder setBirthday(Date date);
        abstract Builder setAge(int age);
        abstract Person build();
    }

    static Builder builder() {
        return new AutoValue_Person.Builder().setId(-1);
    }

    @Key @Generated
    public abstract int getId();

    public abstract String getName();
    public abstract Date getBirthday();
    public abstract int getAge();
}

The processor will generate a PersonType class contain the attributes of Person which is used to construct and create instances of Person by the library when needed.

Example of an entity with a foreign key reference to the previously defined Person type:

@Entity
@AutoValue
public abstract class Phone {

    public static Phone create(int id, String phoneNumber, boolean normalized, int ownerId) {
        return new AutoValue_Phone(id, phoneNumber, normalized, ownerId);
    }

    @Key @Generated
    public abstract int getId();
    public abstract String getPhoneNumber();
    public abstract boolean isNormalized();

    @ForeignKey(references = Person.class)
    public abstract int getOwnerId();
}
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